The present invention relates to an exhaust gas cleaning device for eliminating particulates such as carbon particles in exhaust gases of an internal combustion engine, particularly to an exhaust gas cleaning device provided with particulates collecting members and a heated air supplying means for burning the particulates collected by the particulates collecting members.
The present invention more particularly relates to an exhaust gas cleaning device provided with two particulates collecting members which alternately collect particulates, and a heated air supplying means by which the particulates previously collected by an inactive particulates collecting member are burnt off.
FIG. 1 shows one example of the conventional exhaust gas cleaning device of such a type as described above, which is disclosed in Japanese published unexamined patent application No. Sho 55-19934.
On the downstream side of an internal combustion engine 1, the exhaust gas cleaning device is disposed so that exhaust gases discharged from the internal combustion engine 1 flow therethrough.
The exhaust gas cleaning device is composed of a housing 4, an inlet port 2 through which the exhaust gases flow into the exhaust gas cleaning device, and an outlet port 3 through which the exhaust gases flow out of the exhaust gas cleaning device.
Within the housing 4, two independent exhaust gas flowing passages 51 and 52 are formed, and in both end portions of the exhaust gas flowing passages 51 and 52, an exhaust gas inlet chamber 6 communicated with the inlet port 2 and an exhaust gas outlet chamber 7 communicated with the outlet port 3 are formed.
In each of the flowing passages 51 and 52, heat resistant filter members 81 and 82 for collecting particulates are provided respectively.
And in the exhaust gas inlet chamber 6, an exhaust gas diverter valve 9 for directing the flow of exhaust gases to either one of the collecting members 81 and 82 is provided. Therefore, the exhaust gases containing particulates such as carbon particles discharged from the internal combustion engine 1 flow into the collecting member 81 as shown by hatched arrows, in FIG. 1, for example.
And the exhaust gases are cleaned while passing the collecting member 81 and are discharged out of the outlet port 3 as shown by white arrows.
The conventional cleaning device shown in FIG. 1, is further provided with a burner 101 and a blower 102 for heating and burning the particulates previously collected by the inactive collecting member 82.
The heated air produced by the burner 101 and the blower 102 is supplied into a heated air supplying passages 511 or 512 through a heated air outlet port 105 by the operation of a heated air diverter valve 91. And the heated air supplied into the heated air supplying passage 511 or 512 flows into the exhaust gases flowing passage 51 or 52. When the exhaust gases flow through the particulates collecting member 81, the heated air is supplied into the heated air supplying passage 512 and flows into the exhaust gas flowing passage 52 as shown by broken arrows. Then, the heated air passes the collecting member 82 while burning the particulates previously collected thereby and mixes with the cleaned exhaust gases in the outlet chamber 7.
The mixture is discharged out of the housing 4 through the outlet port 3.
When the volume of the particulates collected by the active collecting member 81 or 82 reaches such a level as to block the flow of the exhaust gases, a differential pressure detector 18, or 19 which measured the pressure difference between the downstream side and the upper stream side of the collecting member 81 or 82, detects the above described timing. And at such a timing, the exhaust gas diverter valve 9 and the heated air diverter valve 91 are changed into the position shown by imaginary lines by means of a manual or automatic control device (not shown). consequently, the passage through which the exhaust gases flow and that into which the heated air is supplied are changed. And the particulates collecting operation is alternated from one particulates collecting member into another particulates collecting member.
Then, the particulates previously collected by the inactive particulates collecting member are burnt off so that particulates are prevented from clogging the particulates collecting member.
The conventional particulates cleaning device as shown in FIG. 1 has such excellent effects as described above. However, it still has various problems to be improved. Namely, it is required to make the device simpler, smaller, and lighter and also to provide a device durable against high temperature.
In the conventional particulates cleaning device shown in FIG. 1, the exhaust gas diverter valve 9, the heated air supplying means 101 and 102, the heated air diverter valve 91, the heated air supplying passages 511 and 512 and a control means (not shown) for operating the exhaust gas diverter valve 9 and the heated air diverter valve 91 coincidently, are required.
Consequently, the whole device becomes so large, heavy and complex that it is difficult to mount such a device in a limited space within a vehicle.
In order to burn the particulates collected by the inactive collecting member, the inactive collecting member must be maintained at a high temperature not less than 600.degree. C.
Therefore, the temperature of the heated air supplied from the heated air supplying means 101 and 102 must be maintained at a temperature as high as 800.degree. C. to 900.degree. C.
Consequently, the heated air diverter valve 91 is exposed to high temperature air flow. And since within the heated air supplying passages 511 and 512, exhaust gases heated by the heated air supplied from the heated air supplying means 101 and 102, stay, the heated air diverter valve 91 is further heated thereby.
As a result, on the valve shaft of the heated air diverter means 91, galling is apt to occur and durability of the valve plate and the valve shaft thereof is decreased.
Accordingly, one object of the present invention is to provide a small sized exhaust gas cleaning device having a simple construction, which is mainly composed of particulates collecting members for alternately catching and collecting the particulates contained within exhaust gases, and a heated air supplying means for heating and burning the particulates previously collected by the inactive collecting member.
Another object of the present invention is to provide an exhaust gas cleaning device of which members, particularly such a member as to be exposed to heated air supplied by the heated air supplying means, can be prevented from overheating.